In Beiswenger U.S. Pat. No. 4,847,606, issued Jul. 11, 1989, a control and display system is provided including a liquid crystal display panel, a light source, and a light detector. Light from the source is directed through the liquid crystal display panel to the light detector, so that the liquid crystal display panel can serve as a gate to either permit passage of the light or to prevent such passage, by means of the electronic circuitry to which the liquid crystal display panel is connected. A control circuit is provided for holding the gating portion of the liquid crystal display panel in generally opaque condition, while preferably sequentially and momentarily clarifying segments of the panel portion. Thus, momentary, sequential, transversely spaced light beams may be generated between the light source and the light detector. A timer and logic circuit is provided for correlating signals received from the light detector with generated, individual, spaced light beams that create the signals.
Accordingly, occlusion of at least one of the individual light beams with an opaque member causes a specific characteristic response by the timer and logic circuit. In other words, when one of the individual light beams is occluded, the timer and logic circuit recognizes this and emits a characteristic signal which might activate a relay, send an instruction to a microprocessor, or cause some other action.
Thus, an electronic switch is provided without moving parts, which is actuated by the desired positioning of a finger or the like to block one of the timed, momentary beams that pass through the liquid crystal display.
In Beiswenger et al. U.S. Pat. No. 4,958,911, issued Sep. 25, 1990, a different type of liquid crystal display module is disclosed, utilizing a housing of C-shaped cross section which carries a liquid crystal display panel, to support and protect the panel and interior elements. The display module may contain interior lighting for back lighting of the liquid crystal display panel. Also, as disclosed in the patent, the module may exhibit a software-variable color display through the use of one or more white or different color light sources and color polarizers so that a multicolor liquid crystal display module may be provided. Additionally, the housing may carry printed circuitry extending between the electronics of the system and the liquid crystal display panel.
By this present invention, apparatus is provided which incorporates features and advantages of the above two patents in a novel and unique manner, to provide a liquid crystal display module which may operate as an electronic switch without moving parts by the occlusion of light beams. At the same time, the display module may exhibit a brightly backlit liquid crystal display, which may be multicolored if desired, and which identifies locations on the liquid crystal display which correspond to switching sites. These locations may change from time to time, as governed by software and optionally depending upon prior switching decisions. The desirable, bright, optionally multicolored display may be correlated with the timed, transverse beams passing across the face of the liquid crystal display which may be occluded by the finger or other opaque object to designate switching choices.
The apparatus of this invention is relatively simple, durable, and of low cost, while exhibiting great flexibility of use that is limited essentially only by the nature of the software that operates the combined switch and backlit liquid crystal display module.